Improved suture pullout through genipin-coated sutures in human biceps tendons with spatially confined changes in cell viability

BACKGROUND

The suture-tendon interface often constitutes the point of failure in tendon suture repair. In the present study, we investigated the mechanical benefit of coating the suture with a cross-linking agent to strengthen the nearby tissue after suture placement in human tendons and we assessed the biological implications regarding tendon cell survival in-vitro.

METHODS

Freshly harvested human biceps long head tendons were randomly allocated to control (n = 17) or intervention (n = 19) group. According to the assigned group, either an untreated or a genipin-coated suture was inserted into the tendon. 24 h after suturing, mechanical testing composed of cyclic and ramp-to-failure loading was performed. Additionally, 11 freshly harvested tendons were used for short-term in vitro cell viability assessment in response to genipin-loaded suture placement. These specimens were analyzed in a paired-sample setting as stained histological sections using combined fluorescent/light microscopy.

FINDINGS

Tendons stitched with a genipin-coated suture sustained higher forces to failure. Cyclic and ultimate displacement of the tendon-suture construct remained unaltered by the local tissue crosslinking. Tissue crosslinking resulted in significant cytotoxicity in the direct vicinity of the suture (<3 mm). At larger distances from the suture, however, no difference in cell viability between the test and the control group was discernable.

INTERPRETATION

The repair strength of a tendon-suture construct can be augmented by loading the suture with genipin. At this mechanically relevant dosage, crosslinking-induced cell death is confined to a radius of <3 mm from the suture in the short-term in-vitro setting. These promising results warrant further examination in-vivo.

Adhesive and biodegradable membranes made of sustainable catechol-functionalized marine collagen and chitosan

We describe bioadhesive membranes developed from marine renewable biomaterials, namely chitosan and collagen extracted from fish skins. Collagen was functionalized with catechol groups (Coll-Cat) to provide the membranes with superior adhesive properties in a wet environment and blended with chitosan to improve the mechanical properties. The blended membranes were compared to chitosan and chitosan blended with unmodified collagen in terms of surface morphology, wettability, weight loss, water uptake, mechanical and adhesive properties. The metabolic activity, the viability and the morphology of L929 fibroblastic cells seeded on these membranes were also assessed. Our results show that the functionalization with catechol groups improves the adhesive and mechanical properties of the membranes and enhances cell attachment and proliferation. These data suggest that the developed marine origin-raw membranes present a potential towards the restoration of the structural and functional properties of damaged soft tissues.

Injectable, porous, biohybrid hydrogels incorporating decellularized tissue components for soft tissue applications

Biodegradable injectable hydrogels have been extensively studied and evaluated in various medical applications such as for bulking agents, drug delivery reservoirs, temporary barriers, adhesives, and cell delivery matrices. Where injectable hydrogels are intended to facilitate a healing response, it may be desirable to encourage rapid cellular infiltration into the hydrogel volume from the tissue surrounding the injection site. In this study, we developed a platform technique to rapidly form pores in a thermally responsive injectable hydrogel, poly(NIPAAm-co-VP-co-MAPLA) by using mannitol particles as porogens. In a rat hindlimb muscle injection model, hydrogels incorporating porosity had significantly accelerated cellular infiltration. To influence the inflammatory response to the injected hydrogel, enzymatically digested urinary bladder matrix (UBM) was mixed with the solubilized hydrogel. The presence of UBM was associated with greater polarization of the recruited macrophage population to the M2 phenotype, indicating a more constructive foreign body response. The hybrid hydrogel positively affected the wound healing outcomes of defects in rabbit adipose tissue with negligible inflammation and fibrosis, whereas scar formation and chronic inflammation were observed with autotransplantation and in saline injected groups. These results demonstrate the value of combining the effects of promoting cell infiltration and mediating the foreign body response for improved biomaterials options soft tissue defect filling applications.

STATEMENT OF SIGNIFICANCE

Our objective was to develop a fabrication process to create porous injectable hydrogels incorporating decellularized tissue digest material. This new hydrogel material was expected to exhibit faster cellular infiltration and a greater extent of pro-M2 macrophage polarization compared to control groups not incorporating each of the functional components. Poly(NIPAAm-co-VP-co-MAPLA) was chosen as the representative thermoresponsive hydrogel, and mannitol particles and digested urinary bladder matrix (UBM) were selected as the porogen and the bioactive decellularized material components respectively. In rat hindlimb intramuscular injection models, this new hydrogel material induced more rapid cellular infiltration and a greater extent of M2 macrophage polarization compared to control groups not incorporating all of the functional components. The hybrid hydrogel positively affected the wound healing outcomes of defects in rabbit adipose tissue with negligible inflammation and fibrosis, whereas scar formation and chronic inflammation were observed with autotransplantation and in saline injected groups. The methodology of this report provides a straightforward and convenient mechanism to promote cell infiltration and mediate foreign body response in injectable hydrogels for soft tissue applications. We believe that the readership of Acta Biomaterialia will find the work of interest both for its specific results and general translatability of the findings.

A novel method for reducing gap formation in tendon repair

Background

This study investigates gap formation in tendon repair using a novel tensioning method.

Hypothesis

The novel stitch will demonstrate less gap formation than the other suture configurations tested.

Methods

Porcine tendons stitched with classic Krackow stitch configurations were compared to a Krackow stitch modified with a proximal Tension-Assist Loop. Each group was cyclically loaded followed by analysis of the tendon-suture construct for gap formation.

Results

The Tension-Assist Loop group produced significantly less gap formation than each of the other stitch groups.

Conclusion

Decreasing early gap formation may be beneficial in allowing early rehabilitation and range of motion.

Is soft tissue repair a right choice to avoid early dislocation after THA in posterior approach?

Background

Dislocation is the second most common complication after total hip arthroplasty (THA). The effectiveness of soft tissue repair to reduce dislocation rate is still debated and thus a meta-analysis was conducted.

Methods

A systematic search in PubMed, Embase, and Cochrane databases was conducted for this meta-analysis. Inclusion criteria: clinical comparative trials on the use of soft tissue repair including rotators and capsule repair in primary THA. The main data outcome were the incidences of early hip dislocation after primary THA. HSS score, incidence of other complications was also included in the outcomes.

Results

A total of 4816 cases were included for the analysis from ten studies (3 RCTs/7 Retrospective trials). Overall, the soft tissue repair group showed a significant lower early dislocation rate and higher HSS score compared to the no repair group; but no significant difference was observed between the two groups in regards to the early dislocation rate in RCT studies only. The capsule repair group showed a significant lower early dislocation rate than no capsule repair group while no significant difference was observed between the rotators repair group and no rotators repair group. In all included studies, 4 greater trochanter fractures, 2 sciatic nerve palsies and 1 infection were reported in soft tissue repair group while no cases were observed in the no repair group.

Conclusions

The efficacy of soft tissue repair is positive but still not conclusive to reduce the early dislocation rate after primary THA while soft tissue repair may bring more other complications. Capsule repair seems more effective than rotators repair only.

No difference between wound closure in extension or flexion for range of motion following total knee arthroplasty: a randomized clinical trial

PURPOSE

Total knee arthroplasty (TKA) is one of the most common surgeries performed in orthopedics. The null hypothesis of the present study was that wound closure in extension or flexion does not have any impact on range of motion (ROM) and clinical outcome after TKA.

MATERIALS AND METHODS

This study was a double-blind prospective randomized clinical trial performed at Kashani Hospital. From 2011 to 2012, eligible patients were consecutively enrolled in the study and randomly assigned in two groups. Soft tissue was repaired in 90° flexion in the first group and in full extension position in the second group. The primary outcome of this study was the flexion ROM after 12 months. Secondary outcome was the knee flexion ROM that was evaluated in the first, second, and fourth week and also 6 months after TKA. The other secondary outcome was the knee society score (KSS) that was evaluated before the surgery and after 12 months.

RESULTS

Of the 85 eligible patients who completed the study, 44 were assigned to extension group and 41 to flexion group. There was no significant difference between demographic variables in the study (n.s). There were no significant differences in ROM between the study groups (n.s). There was no significant difference in KSS between study groups before and after the study period (n.s).

CONCLUSION

It is concluded that wound closure in flexion or extension position after TKA does not affect postoperative flexion ROM and KSS.

LEVEL OF EVIDENCE

I.

Effectiveness and safety of the posterior approach with soft tissue repair for primary total hip arthroplasty: a meta-analysis

BACKGROUND

Repair of soft tissue in favour of the posterior approach for total hip arthroplasty is still under discussion and few studies are assessing this issue. Therefore, we performed a meta-analysis to compare the effectiveness and safety of the posterior approach for total hip arthroplasty with and without soft tissue repair. We focused on these questions as follows: does primary posterior approach for total hip arthroplasty with soft tissue repair has better result regarding dislocation rate, Harris hip score and the sciatic nerve palsy rate compared with posterior approach without soft tissue repair.

PATIENTS AND METHODS

We conducted electronic literature searches using CENTRAL (Issue 1 of 12, Jan 2014), PUBMED (1980 to Jan 2014), and EMBASE (1980 to Jan 2014). Clinical studies evaluating the posterior approach for total hip arthroplasty with and without soft tissue repair were collected. After independent study selection by 2 authors, data were collected and extracted independently. The methodological quality of the studies was assessed by the Cochrane Collaboration's tool for assessing risk of bias and the Newcastle-Ottawa Scale.

RESULT

Seven clinical trials with 4594 hips using the posterior approach for total hip arthroplasty were included. The pooled data indicated a lower rate of dislocation (OR: 0.14, 95% CI: 0.08-0.26, P<0.00001) and higher Harris hip score (1.75, 95% CI: 1.19 to 2.32, P<0.00001, I(2)=26%) after the posterior approach to total hip arthroplasty using soft tissue repair than without using soft tissue repair. There was no statistical difference in sciatic nerve palsy between the use of soft tissue repair and without it in posterior approach to total hip arthroplasty (OR: 5.34, 95% CI: 0.25-112.25, P=0.28).

DISCUSSION

Our meta-analysis included data from more studies than were previously available and demonstrated that the use of soft tissue repair and without it in posterior approach to total hip arthroplasty are similar in safety. Using repair resulted in a lower dislocation rate and higher Harris hip score than without repair.

LEVELS OF EVIDENCE

Level 2 meta-analysis of low-powered prospective randomised trial.